| 标题 | 使用UART与PC通信实现msp430g2553单片机超声波测距示例 |
| 内容 | 这篇文章主要介绍了使用UART与PC通信实现msp430g2553单片机超声波测距示例,需要的朋友可以参考下. 适用于msp430g2553单片机 使用到了hc-sr04超声测距模块，使用UART与PC通信。 代码如下: #include long current_time;//最近一次测得时间 /*MyPro*/ #define LED_1 BIT0 #define SW_2 BIT3 #define TA1_1 BIT2 //TA0.1 HC-SR04 Echo #define TRIG BIT4 //HC-SR04 Trig #define ACCU_GRD 7 //Accuracy Grade "xxx.x"+'' #define MIN_UNIT_TO1M 1000 //1 m to 1 mm /*TIMER0*/ #define SOUR_CLK 1045000 #define DIV_CLK_1 1 #define SYS_CLK_SIG_1 SOUR_CLK/DIV_CLK_1 #define DISTANCE 45//dm #define TIMER_RIG_MAX 0xffff #define MAX_TIME_1 DISTANCE*2/34*SYS_CLK_SIG_1 #ifdef MAX_TIME_1 #define SYS_CLK SYS_CLK_SIG_1 #endif #define UART_TXD BIT2 void init_timer1() { P2SEL |= TA1_1; //TA1.1 CCI1B be used P2DIR &= ~TA1_1; TA1CTL = MC_0 + TASSEL_2; //TimerA_0 stop mode,clock=1Mhz TA1CCTL1 = CCIE + SCCI + CCIS_1 + SCS + CAP + CM_2; //TA0CC1 capture mode + down edge } /*UART*/ void init_uart() //USCI 初始化函数 { UCA0CTL1 |= UCSWRST; //初始化串口寄存器 UCA0CTL1 |= UCSSEL_2; //选择子系统时钟 1.045MHz UCA0BR0 = 0x6d; //波特率为9600 UCA0BR1 = 0x00; P1SEL |= UART_TXD; P1SEL2 |= UART_TXD; P1DIR |= UART_TXD; //将P1.2设为第二功能 UCA0CTL1 &= ~UCSWRST; //初始化结束 } long cal_distance() //通过测得时间计算距离 { return (long)((340*(0.5000*current_time/SYS_CLK)*MIN_UNIT_TO1M)); } void delay() //粗略延迟 { unsigned char i,j; for(i=124;i>0;i--) for(j=8;j>0;j--); } static char * translater(long distance) //将测得的距离以字符串形式存储 { static char trans[ACCU_GRD]; int i; long f; trans[0]=' '; if(distance) for(i=1,f=MIN_UNIT_TO1M;i { if(i==4) { trans[i] = '.'; continue; } trans[i] = '0'+ distance/f; distance %= f; f /= 10; } trans[ACCU_GRD-1] = ''; return trans; } void once_pro() //发一次超声波 { if(TA1CCTL1 & COV) TA1CCTL1 &= ~COV; if(!(P1IN & BIT3)) { TA1R = 0; P1OUT |= TRIG; //Trig 10 us 高电平 _EINT(); TA1CTL |= MC_2; //continue mode P1OUT &= ~TRIG; P1OUT |= LED_1; while(TA1CCTL1 & CCIFG); //等待 捕捉中断结束 } else { P1OUT &= ~LED_1; _DINT(); } } void uart_txstring(char *string) //UART_TX 发送一个串 { int i=0; while(string[i++]) { switch (i) //过滤无效 '0' { case 1:if(string[i]=='0') continue; case 2:if(string[i]=='0'&&string[i-1]=='0') continue; } UCA0TXBUF = string[i]; delay(); } } /*UART_ISR*/ #pragma vector = USCIAB0TX_VECTOR __interrupt void usci_txdistance() //向 PC 发送 测得的距离 { uart_txstring("nr"); uart_txstring(" Current "); uart_txstring(" distance: "); uart_txstring(translater(cal_distance())); uart_txstring(" cm"); IE2 &= ~UCA0TXIE; } /*TIMER0_INT_ISR*/ #pragma vector = TIMER1_A1_VECTOR __interrupt void capture() { current_time = TA1CCR1; TA1CTL &= ~MC_2; TA1CCTL1 &= ~CCIFG; //清CC1中断标志位 IE2 |= UCA0TXIE; } /*Main*/ void main() { WDTCTL = WDTPW + WDTHOLD; //关狗 DCOCTL = 0; BCSCTL1 = CALBC1_1MHZ; DCOCTL = CALDCO_1MHZ; P1OUT = 0; P2OUT = 0; P1REN |= SW_2; P2REN |= TA1_1; P1OUT |= SW_2; P1DIR &= ~SW_2; P1DIR = TRIG + LED_1; init_timer1(); init_uart(); while(1) { int c = 8; while(c--) delay(); if(TA1CCTL1 & CCIFG) TA1CCTL1 &= ~CCIFG; once_pro(); } } |
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